There is no firewall in the base, and we have several servers running at various ports, apache, vsftpd, tftpd, sshd to name a few, and none of them complain. This is the first time I've seen an error like this in TC, which leads me to think it would be in this script/app.

Thanks a lot , actually I have the same problem. A friend's PC wanted to use some engineering app ( Hspice ), but the licensing manager ( FELXnet ) keep reporting error, it says that "Failed to open the TCP port number in the license file. ".Finally, I found your post, and it reminded me of checking the C:\windows\system32\drivers\etc\ and I found the "protocol" file has been missing. So I copy a correct one from other system. Then it all works well.